The OTN, which is a transport network based on Wavelength Division Multiplexing (WDM) technology on an optical layer organization network, is a new generation of “digital transport system” and “optical transport system” standardized by a series of recommendations from the International Telecommunication Union Telecommunication Standardization Sector (ITU-T), including G.872, G.709 and G.798 etc. The OTN can solve the problems of the lack of wavelength/sub-wavelength service scheduling ability of conventional WDM networks, and weak networking capability and protecting ability etc.
With the rapid development of data services, especially with the development of broadband and video services, new requirements have been made on transport networks of operators. A transport network should be able to adapt to the increasingly huge bandwidth. More importantly, the transport network is required to be able to perform service scheduling rapidly and flexibly and improve convenient network maintenance and management to meet service demands.
OTN technology includes a complete system structure of optical layers and electric layers. The network of each layer is provided with a corresponding managing and monitoring mechanism, and both the optical layers and the electric layers are provided with network survivability mechanisms. The circuit cross granularity can reach 1.25 G/2.5 G/10 G/40 G through the cross function of an OTN device based on an Optical channel Data Unit (ODUk), thus realizing flexible scheduling and protection of large-granule services. OTN technology provides a plurality of cross granularities, i.e. ODU0 (1.25 Gbit/s), ODU1 (2.5 Gbit/s), ODU2 (10 Gbit/s) and ODU3 (40 Gbit/s), and ODU4 which is being defined, to realize faster transmission of 40GE/100GE signals. High-speed cross granularities have higher cross efficiency, which enable devices to realize great cross connecting capability more easily, so that cost of devices can be reduced.
In the prior art, corresponding cross granularities are generally matched according to different rates of customer services in OTN cross devices. For a single board at the line side, although services of an optical interface are fixed OTN services which will not change along with changes of cross granularities, it is still needed to manually designate cross granularities by network managers to perform normal communication because of limitations of implementation mechanisms.